In this paper, a low-power high-speed CMOS full adder core is proposed for embedded system. Based on a new three-input exclusive OR (3-XOR) design, the new hybrid full adder is composed of pass-transistor logic and static CMOS logic. The main design objectives for the full adder core are providing not only low power and high speed but also with driving capability. Using TSMC CMOS 0.35-mum technology, the characteristics of the experimental circuit compared with prior literature show that the new adder improves 1.8% to 35.6% in power consumption, 11.7% to 41.2% in time delay of Co, and 13.7% to 91.4% in power-delay product of Co. The circuit is proven to have the minimum power consumption and the fastest response of carry out signal among the adders selected for comparison. Due to the low-power and high-speed properties, both the new exclusive OR circuit and the new full adder can be efficiently integrated in a system-on-a-chip (SoC) or an embedded system.